Plain English Meaning
An airplane that has just one engine.
Full Definition
Describing an airplane equipped with one powerplant (engine). Used to classify aircraft for training, certification, and operational purposes, and to distinguish them from multi-engine airplanes which have two or more engines.
Context Anchor
Seen in airplane descriptions, training discussions, and handbook sections about how an airplane handles, stalls, climbs, glides, or recovers using power.
Why Pilots Care
Determines the specific emergency procedures, performance data, and pilot certification requirements that apply when the single power source fails.